1. Field of the Invention
The present invention relates to an image forming apparatus using an electrophotographic system having a copy function of scanning a document and printing the scanned image on a sheet of recording paper. More specifically, the present invention relates to an image forming apparatus enabling immediate replenishment of consumable supply when the remaining amount of the consumable supply used for image formation is detected to be low or the consumable supply is detected to be used up, so that the time period in which the apparatus is inoperable can be made shorter.
2. Description of the Background Art
An image forming apparatus having the copy function scans a document to form image data, and on a recording medium such as plain paper or an OHP, forms an image of the scanned document. Considering the speed of image formation, image quality and cost, the electrophotographic system is often used in the image forming apparatus. The number of apparatuses having a plurality of basic functions (operation modes) such as a facsimile function (hereinafter “facsimile” may also be denoted as FAX or fax), a network-supported printer function and a scanner function in addition to the copy function, such as MFPs (multi-function peripherals), is increasing.
In such an electrophotographic MFP, when an image is formed on a sheet of recording paper, toner is consumed (for a monochrome MFP, monochrome toner, and for a color MFP, toner of four colors, for example, C (cyan), M (magenta), Y (yellow) and K (black)). At the same time, recording paper is also consumed. If any of such consumable supplies is used up, the apparatus fails to operate. Therefore, it is necessary to detect that the consumable supplies are used up (referred to as “end state”) or the remaining amount of consumable supplied becomes lower than a prescribed amount (referred to as “near end state”), and to maintain the amount of consumable supplies to be always higher than the prescribed amount.
For this purpose, conventionally, sensors for detecting remaining amounts of consumable supplies are provided at various portions of the MFP, and when any of the consumable supplies attains to the near end state or end state, an alarm is given to the user, urging replenishment. In response to the alarm, the user can replenish the consumable supply ahead of time. As long as the user responds to the alarm appropriately, the image forming apparatus can continuously execute the image forming process. If the user fails to replenish the consumable supply and the consumable supply attains to the end state, the image forming apparatus cannot execute the image forming operation.
Both in the near end state and in the end state (hereinafter both states will be simply referred to as “near end state” and in the present embodiment, the near end state encompasses the end state), it is necessary for the user to stop the operation of image forming apparatus, before replenishing the consumable supply. Specifically, it is necessary for the user to stop the operation of image forming apparatus, and to exchange a used toner bottle in the image forming apparatus with a new toner bottle, or to draw out a paper feed cassette and load sheets of recording paper. During this period, the image forming apparatus cannot operate.
It is often the case that such an MFP is connected to a network and to a public line. As a result, the MFP comes to be shared by a plurality of users at various different places. Since the users request printing at different timings, the MFP is kept powered-on for a long period of time and, therefore; it is desired to reduce power consumption. If the MFP has the facsimile function, it is common to have the main power of MFP kept on all day, including night time and holidays. Thus, the need for reducing power consumption is increasing.
From the reasons described above, it is a common practice to turn off the power or to automatically change the state of MFP to an energy saving mode in which the power consumption is reduced, if a prescribed time period passes without any request for operation in the MFP with the main power on. Typically, power supply to some modules is stopped in the energy saving mode. Generally, the energy saving mode is cancelled when the user operates a key to start printing or copying, or when a print request is received through the network.
In the conventional MFP, however, transition to the energy saving mode is prevented if an alarm is being given to the user that any consumable supply, such as the sheet of recording paper or the toner, is in the near end or end state. The reason for this is that replenishment of consumable supply as soon as possible is desired. By way of example, if there is a display alarming the user that the sheet of recording paper is used up, the MFP does not enter the energy saving mode. In such a case, if the consumable supply is not replenished by some cause or other, transition to the energy saving mode of the MFP never takes place. As a result, power consumption of the MFP undesirably increases.
In consideration of such a problem, Japanese Patent Laying-Open No. 2006-194922 (hereinafter referred to as “'922 Reference”) discloses an electronic device that enters the energy saving mode in response to a request to make a transition to the energy saving mode, even if there is any factor that causes an alarm.
The electronic device disclosed in '922 Reference has the energy saving mode in which the power consumption is reduced in the standby state, as one of its operation modes. If there is any cause of alarm in the electronic device, for example, if the sheet of paper is used up, the toner is used up or a paper jam occurs in the normal operation mode, an alarm is displayed on an operation display unit. Even when an alarm is displayed on the operation display unit, the electronic device automatically enters the energy saving mode if it receives an operation to enter the energy mode by an operator or if a prescribed time period passes without any operation. The electronic device has an LED that lights green when it is in the energy saving mode, and an LED that lights red when there is any cause of alarm in the energy saving mode. Even though the electronic device is in the energy saving mode and the generally used operation panel is not is operation, the user can recognize that there is some cause of alarm if the LED lights red.
According to '922 Reference, it is possible to reduce power consumption without impairing the operability of the electronic device. By way of example, even when the device enters the energy saving mode with the toner in the end state, it is possible to give an alarm to the user.
The technique described in '922 Reference, however, still has a room for improvement. Specifically, even if the technique of '922 Reference is adopted, it is still necessary to stop the operation of the electronic device in order to replenish the consumable supply. For the time period required for replenishing the consumable supply, the electronic device cannot execute any process that uses the consumable supply. While the electronic device is powered on, it is desirable to make as long as possible the time in which electronic device is usable. Such a problem cannot be solved by the technique disclosed in '922 Reference.